BACKGROUND AND PURPOSE: Impairment of macrophage polarization from a proinflammatory macrophage type 1 (M1) population to an anti-inflammatory macrophage type 2 (M2) population is a hallmark of poor wound healing. In this study, we aimed to evaluate the distribution of M1 and M2 macrophages and to analyze their association with healing in aneurysms embolized by endovascular coiling. MATERIALS AND METHODS: Elastase-induced aneurysms were created in female rabbits and subsequently embolized with platinum coils. Aneurysm occlusions were evaluated with angiographic imaging at 1 (n ¼ 6), 3 (n ¼ 5), or 6 (n ¼ 6) months. Aneurysm tissues were harvested for histologic analysis, quantification of M1 and M2 macrophages by immunofluorescence, and collagen deposition determined by Masson trichrome staining. Histologic grading of aneurysm healing was also performed. Untreated aneurysms were used as controls (n ¼ 6). RESULTS: The M1 macrophage population was highest at 1 month posttreatment, progressively decreasing at 3 and 6 months. The M2 macrophage population progressively increased at 3 and 6 months posttreatment. The highest collagen deposition was at 6 months posttreatment. We found a moderate-to-weak direct correlation between the percentage of M2 macrophages and collagen deposition, as well as total histologic scores overall, and a strongly positive direct correlation between the percentage of M2 macrophages and total histologic scores at 6 months posttreatment.

Systemic statin administration after platinum coil embolization of unruptured aneurysms in a rabbit model does not improve aneurysm occlusion rates at 4 weeks.

O-016 Figure 1 M1 and M2 macrophage expression in aneurysm tissues after endovascular coiling for three treatment-to-sacrifice time groups. A) mean number of M1 macrophages; representative confocal microscopy image of M1 macrophages (60X oil magnification) at 1 month (B), 3 months (C) and 6 months (D); E) mean number of M2 macrophages; representative confocal microscopy image of M2 macrophages (60 X oil magnifications) at 1 month (F), 3 months (G) and 6 months (H). *P<0.05; **P<0.